A high density, multi channel ink jet printhead is disclosed in U.S. Pat. No. 5,016,028 issued May 14, 1991 to Temple. The printhead includes a sheet-like body of piezoelectric material poled in a direction normal to the sheet and having a plurality of parallel channels mutually spaced in an array direction normal to the length of the channels. Each channel is defined by facing side walls and a bottom surface extending between the side walls. Electrodes of a suitable metal such as nickel chromium, i.e. nichrome, are provided on opposite sides of the side walls to form shear mode actuators for effecting droplet expulsion from the channels associated with the actuators. Each electrode extends substantially along the length of the corresponding side wall. A top sheet is disposed parallel to the bottom surface of the channels and is bonded to the tops of the side walls to enclose the channels.
A problem arises in effecting a suitable bond between the top sheet and the piezoelectric body when the body is of a porous piezoelectric ceramic such as PZT. For most efficient print head operation, the bond between the top sheet and the tops of the side walls defined by the body, needs to be as stiff (non compliant in the shear mode) as possible. To form non compliant bonds in the shear mode, adhesives such as thermosetting plastics need to be applied in very thin layers. Layers of the desired thinness are difficult to achieve however on a porous surface such as PZT.